1. Field of the Invention
The present invention relates to an alarm device which detects an abnormal condition such as a fire and emits an alarm, and also wirelessly transmits a signal to other alarm devices to facilitate linked alarm output.
Priority is claimed on Japanese Patent Application No. 2008-075037, and Japanese Patent Application No. 2008-075119, the contents of which are incorporated herein by reference.
2. Description of Related Art
Conventionally, household alarm devices (hereafter “alarm devices”) which detect abnormal conditions such as fires or gas leaks in a residence and issue an alarm have become prevalent, and in recent years there is a proposal for ones that monitor for abnormal conditions such as a fire on a room-by-room basis by installing a plurality of alarm devices throughout a single residence (refer to Japanese Unexamined Patent Application, First Publication No. 2007-094719, for example).
When a plurality of alarm devices are installed in a single residence in this manner, a person who is present in a different room from the room where the abnormal condition occurred may not hear the alarm sound, giving the fire or other problem a chance to spread. Therefore, by connecting the alarm devices to the others using wires, when a particular alarm device detects a fire and issues an alarm, the signal is sent to the other alarm devices so that the alarm is emitted simultaneously, thereby realizing a linked alarm system.
However, because providing a wired connection between alarms requires that wiring be installed, a problem arises in terms of increased costs. This problem can be resolved by employing wireless alarm devices. Furthermore, accompanying the recent reduction in power consumption of the ICs used in modern wireless circuits, even when operating in a state of constant readiness to receive alarm signals from other alarm devices, battery life that is sufficient from a practical standpoint, for example five years or longer, is assured, and the practical use of wireless alarm devices is thus advancing.
However, with wireless alarm devices which enable linked alarms output, a problem exists whereby the surrounding environment has an effect on communication range, preventing a stable communication environment from being secured on an ongoing basis. For example if wireless alarm devices are installed in each room in a residence, communication may be impeded when the door to a room is closed. When the communication environment is adversely affected in this way, a problem may occur in that when a given alarm device detects a fire or other abnormal condition and issues an alarm, an alarm cannot be output from the other alarm devices serving as linkage destinations.
A first object of the present invention is to provide an alarm device capable of performing reliable linked alarm output wirelessly between a plurality of alarm devices.
On the other hand, with a conventional wired alarm device, when a plurality of alarm devices are wired together, and a given alarm device detects a fire, the linkage source alarm device which detected the fire and the linkage destination alarm devices output different alarm sounds. For example a siren followed by a voice message “The fire alarm has activated. Please verify.” may be output continuously in the linkage source alarm device which detected the fire, and on the other hand the linkage destination alarm devices may continuously output a siren followed by a voice message “The fire alarm in another room has activated. Please verify.”
On the other hand, in the alarm device, an alarm stop switch which also functions as a test switch is provided, and the alarm can be stopped when the switch is operated during alarm output by a pull cord or other means. In the case of alarm devices linked by wiring, when the alarm stop switch of the linkage source alarm device which detects the fire is operated, the audible alarm of all alarm devices stops. Furthermore, when the alarm stop switch of a linkage destination alarm device is operated, only the audible alarm of that alarm device stops.
Incidentally, in this type of alarm device, a function is provided for detecting and reporting failures such as a low battery revealed by a drop in battery voltage. A low battery is detected when the battery voltage has dropped to the minimum voltage required for the alarm device to operate not ally for a span of 72 hours, whereupon an audible alarm in the form of a short beep at one minute intervals is output, for example.
However, when an alarm device is installed in an unoccupied room, even if a low battery is detected and an audible alarm is output, there is a danger of the battery going flat if the alarm goes unnoticed by a user.
A second object of the present invention is to provide an alarm device which, when a failure occurs among a plurality of alarm devices which perform linked alarm output, reliably informs users of such and enables the appropriate response to be taken.